Often, in such joints, the crimp-ferrule is blind-ended, whereby it is impossible to see whether the tubing is fully inserted into the ferrule, neither before nor after the crimping operation has been carried out. The possible consequence of improper insertion of the rubber tubing into the ferrule is that the connection is liable to premature failure, i.e to leak, or even to burst apart.
It has been the traditional practice to provide a sight-hole in the crimp-ferrule, at or near the blind end thereof, for inspection purposes. The sight-hole, or witness-hole, provides a window through which an inspector can determine whether rubber is or is not present within. The sight-hole is located at a place where, if rubber is visible through the sight-hole, that fact is an indication that the hose has been fully, i.e properly, inserted.
It is notoriously difficult for even the most conscientious inspector, upon visually checking thousands of hose connections, to pick out the tiny fraction in which the rubber is not visible through the sight-hole. However, hitherto, it has not proved practically reliable to detect the presence or absence of rubber, through the sight-hole, by the use of automatic detection equipment.
The invention is aimed at providing, in a hose connection to a pipe or other fitting, a test for detecting whether the rubber tubing has been fully inserted into the ferrule. One aim is to provide a test that is operable automatically, and is highly reliable at detecting the difference between proper and improper insertion.